The recent arrival of the Subhub’s appendages brings the build phase of this fully integrated tidal platform to a conclusion. QED will soon validate claims that Subhub provides a “tidal array in a day” along with easy and quick recovery for maintenance at the surface or in sheltered water.

The Subhub is a universal foundation platform and deployment / recovery method suitable for any type of turbine. It can be modified to capture the benefits of both Horizontal Axis Turbines (HATs) and/or Vertical Axis Turbines (VATs). The platform’s ballasting methods can work equally well with wave turbines as well.

The principle benefit of the Subhub is its ability to install a fully integrated, gravity based structure to the seabed including turbines, PTO equipment, ballast. It does this in a single and quick offshore operation using small support vessels which are commonly available making it a very cost effective solution.

However, Subhub also provides large performance advantages by steering the turbulent flows into the turbines enabling them to perform as expected in rated flow conditions significantly increasing site capacity factors and energy yield.

Subhub with all her appendages including Cross Beam to support the tidal turbines and the Subsea Manifold in the background to control the Subhub remotely from small support vessel or barge.

Measurements being taken on the Cross Beam for the fairing structure to be added with the tidal turbines and rotor blades lined up for assembly onto the Cross Beam post launch.Subsea manifold with the port and starboard umbilicals offered up ready to connect all the pneumatic, hydraulic, data and power cables.

QED are delighted to announce the appointment of Dr. Corey Badger. Her role maintains the sophisticated CFD numerical capabilities employed as part of the Subhub tidal platform design process. This uses High Performance Computing (HPC) capabilities which clusters all the high end workstations together to provide 32 core processor power with shared memory of 256GB enabling massive numerical models to run quickly providing tangible results on turbine performance within weeks rather than months. These capabilities are part of the companies ANSYS Fluent CFD package which offer state of the art modelling methods.

QED offers these capabilities and services to other companies working in the sector including turbine and project developers. This includes the performance characterisation of tidal turbines both with and without the Subhub tidal platform to assess the impact of the structure on their performance.

More recently the company has been working with Queens University Belfast (QUB) to assess the impact of Subhub on turbulence within the TTT3 project. This involves taking ‘as measured’ ADCP measurements and determine the turbulence content in it and applying turbulence factors to a numerical model of a rotating turbine in steady state condition that provides accurate general loading and performance data (Ct, Cq, Cp). The next stage is to run these models in a transient solution providing unsteady loading results of the turbine and Subhub.

CFD numerical model of the TTT3 turbines including ‘as measured’ turbulence and flow conditions used to predict the steady state performance characteristics and unsteady loading conditions.

There have been some interesting results to date and this work will be a large part of Corey’s role to validate the claims that Subhub has major performance and unsteady loading benefits on tidal turbines. Further claims of reducing the effect of tidal shear on seabed mounted devices and lessening the issue of turbulence and cross flows on the turbine blades by steering the flow into the turbines like stators of a pump jet.

Corey has also taken on the development of the company’s Tidal and Wave Energy Evaluation Tools (TWEET). The main module of TWEET takes as measured or theoretical tidal harmonic models along with CFD/BEM performance data of the turbines and projects the energy generated from the inlet condition over a period of a year or the life of the project. Monte Carlo simulations can then be run from within TWEET to determine the economic viability of the project.

Monte Carlo simulations for the cost of the mass including fabricated mass and ballast mass.

The company has also started building its own GIS mapping tool to store and maintain site data including bathymetry, flow rates, positions of moorings, pictures and videos of seabed conditions and mammal, bird and fauna sightings for EIA studies.

Output from QEDs GIS mapping tool showing the position of the selected Subhub test sites at the QUB test centre along with flow data and bathymetry.

Corey brings new capabilities to the company having completed her Ph.D in multiphase flows using OpenFOAM, the open source CFD package. She has used the Edinburgh Parallel Processing Centre (EPCC) super computer to complete her Ph.D and now QED Naval have implemented Linux on a dedicated compute server to run OpenFOAM capable of completing very large numerical calculations in excess of 10 million cells. Transferring these models over to the EPCC will provide fully validated results within days rather than weeks.

QED Naval has successfully completed the final round of funding to complete the sea trials of their Subhub tidal turbine foundation platform. The funds have been raised through the existing shareholding with 75% raised through Kelvin Capital and the remaining through Scottish Investment Bank (SIB).

The funds will be used for ballasting trials to demonstrate how quickly and easily Subhub can be installed and recovered in real sea conditions (in waves and tide). The trials will also demonstrate the significant increase in energy generated by mounting the turbines on the Subhub platform (up to a 40% increase in power output) thereby increasing capacity factors and making some sites commercially viable. QED will then assess the performance impact of Subhub on tidal turbines in accordance with the IEC standards.

QED Naval are now recruiting 4 new positions building its team to support the next stage of trials and the ongoing technical development of the Subhub leading to the companies first commercial deployments. See the Team/Join Us link for further information. In short, the company is looking for:

Electrical & Instrumentation Control Engineer

Naval Architect

Fluid Loading CFD Engineer

Structures Design Engineer

QED Naval have been collaborating with Queen’s University Belfast (QUB) and the Centre for Advanced Sustainable Energy (CASE), part of Invest Northern Ireland’s £10m centre for industry-led sustainable energy research. Specifically, this collaboration has been part of the Tidal Turbine Testing project (TTT), which is used to determine the impact of turbulence on the prediction of tidal turbine performance. In summary, flow measurements have been recorded using ADCP systems to try and understand the behavior of the turbines in turbulent conditions. These measurements have then been used by QED Naval to predict the performance of a hypothetical turbine and then determine the impact of Subhub on the performance with impressive results.

Streamlines through the semi-duct of the Subhub and sliding mesh turbine.

As a result of this collaboration QED Naval have decided to test the Subhub in Strangford Lough at the QUB tidal test site, leased from the Crown Estate.

Also, as part of the ongoing support, QED Naval are sponsoring 2 industrial Ph.Ds, one on turbulence modelling and the other on remote sensing mapping of resources as part of their involvement with The Bryden Centre supported by the EU’s INTERREG VA Programme. There are still vacancies for these posts so please follow the link for contact details if this is of interest to you. These studentships are not exclusive to Northern Ireland or Ireland but also includes the University of the Highlands and Islands so it has broad appeal.

On Saturday 13th January 2018, Subhub was successfully moved out of the fabrication shed where Cimpina built the main hull. Their support throughout build and integration stages has been nothing short of exemplary.

The move was completed by Mar Train Heavy Lift Limited who managed the job with the utmost professionalism. The move involved removing part of the front of the fabrication shed, a process that Cimpina have managed themselves and with the help of local contractors.

QED Naval have completed the initial outfit and furnishing of all the internal ballast systems made up of UK based supply chain companies for all the hydraulic, pneumatic, electrical and control systems. The project has employed over 200 people and contractors which demonstrates the wealth that can be injected into the UK economy if tidal energy was better supported by the UK government.

The lay down area within the Titanic Quarter is ideal for completing the final stages of commissioning including the fitting of the X-beam that supports three tidal turbines. This variant of the Subhub has been designed for Schottel SIT 250 turbines each rated at 70kW. Broadly speaking, this equates to generating sufficient power to support around 60 homes.

Full systems testing can be carried out from this location which is an ideal location to base QED Naval’s operations. It allows QED to build confidence and train staff in the installation and recovery procedures.

Customers are invited to see the Subhub for themselves. Please contact Jeremy Smith on +44 (0) 131 557 8049 if you wish to arrange a visit.

Subhub exiting from the fabrication shed. A tight squeeze.Subhub on the road to her new lay down area.Mar Train maneuvering Subhub around a tight bend in the Port of Belfast.Subhub simulation test setup with the ballast control and equipment containers close by along with the modular solid ballast blocks. Note the 2t Operations Model alongside the ballast blocks.

Transportation contractors, Mar Train, completed a trial lift of the Subhub recently to reduced the risks associated with the load out to the quayside at Harland & Wolffe, Belfast, Northern Ireland.

The weight of Subhub throughout the build has been controlled in order to achieve the load out requirements which were proven by the Mar Train test lift.

As a result QED have refreshed all their stability models to ensure compliance with each load condition i.e. load out, transit to site, installation and recovery, and in-service conditions. Damage conditions and reserve buoyancy have also be considered carefully.

Exit is planned early in the new year, shortly after, the Subhub will be launched for final ballast testing and then towed to site ready for installation.

This load out phase of the project demonstrate how a tidal power plant such as Subhub (210kW) can be fully integrated at the quayside and deployed, installed and recovered in a single, quick offshore operation. There are no other moorings to lay just a single dry mate connection to make to an export cable which is grid compatible.

Mar Train test lift carried out using their 7-axle trailer to reduce the risk of the exit from the fabrication shed.Mar Train take up the full load and lift Subhub off the upstands.

QED Naval have completed the commissioning of all onboard ballast and instrumentation systems ready for testing and launch early in 2018. This community version is a big step to proving the claims about competing with offshore wind for CFDs at utility scale.

QED Naval is working with Schottel Hydro on this 190kW version which is competitive, in terms of LCOE, with diesel generation for island communities’ or offshore power generation for aquaculture offering excellent niche market opportunities recently forecast by Aquatera.

However, Subhub was always designed for utility scale projects, removing the requirement for large specialist vessels at expensive day rates and multiple marine operations offshore. Where Subhub requires only a single offshore operation using smaller vessels and/or barge at low day rates.

Fundamentally, the concept of Subhub using buoyancy and good submerged stability to install the turbines scales very well. Also, the ballast ratios, for the required on-bottom weight to secure the turbines on the seabed, scales in their favor. The utility version is more slender and uses simpler construction methods reducing fabrication costs still further enabling the acceleration effects of the semi-duct to be applied to every turbine. QED’s latest CFD models when combined with a tidal harmonic models for the site and power curve of the tidal turbine show increases in yield of up to 50% year on year when compared with typical monopile structures. Subhub effectively increases the capacity factors of the site.

An independent report by a Master Mariner has stated that installation and recovery costs of a utility scale Subhub can be reduced by 50 to 90% compared with current methods. The seaworthy design, stability when submerged and the control of the ballasting process make the Subhub less sensitive to wave loading during installation. This allows it to be installed and recovered over broad weather windows and hence the availability for maintenance is higher. This attributes a large reduction in maintenance costs.

QED Naval pride themselves on the understanding of the combined effects of wave and tidal loading learning huge amounts from their tank testing at Flowave, open water testing at The Underwater Centre in Loch Linnhe. Their collaborations with EMEC/FORESEA, and QUB as part of the Tidal Turbine Turbulence (TTT3) project have provided unrestricted access to real measured tidal data using ADCP systems for accurate tidal modelling and turbulence measurements. QED’s work on turbulence modelling in collaboration with the National Oceanographic Centre (NOC) is thought to be class leading and provides more assertive results for energy yield calculations.

All this learning has been combined into Monte Carlo simulations for various projects QED have assessed which provides a sound basis to presenting the LCOE figures and making project finance decisions.

All these claims will be assessed in the next stage of testing to be commenced early 2018.

Aft view of Subhub showing tripod leg structure and semi-duct for accelerating the tidal flow into the turbine.

QED Naval are pleased to annouce the acceptance of the Subhub – Kraken’s main hull fabrication including all outfit hotwork.

An important part of the acceptance was the main hull lift off the cradle and supporting structure onto the Subhub’s main leg structure to fully support her ample weight.

Factory Acceptance Tests (FATs) which pressurised each of the ballast tanks were completed successfully along with all the load testing of the lifting equipment including the main hull lifting lugs (68t load) and the modular solid ballast blocks (2 off) each weighing 20t.

All the welding plans and Non-Destructive Tests (NDTs) have been completed and approved.

QED Naval would like to take the opportunity to thank their prime contractors, Cimpina, in their support and commitment that they have provided to get the project to this point of completion.

QED Naval have now taken responsibility for all the outfitting of the Subhub and has completed all the internal outfit. Kraken is now awaiting painting which will be completed in early October.

QED Naval are currently commissioning and testing all the ballast and instrumentation systems prior to a planned launch in early 2018.

Subhub aft end showing the semi-duct that accelerates the flow into the turbines for increased power output and yield.Subhub undergoing FATs pressure testing where each tank is pressurised to ensure water tightness and hydrostatic load capability.The power of buoyancy! Amazing to think that this small compressor can lift almost 200 tons from the seabed in such a stable way over such large tidal and wave weather windows.

QED Naval and their selected fabricators, Cimpina based in Northern Ireland, are soon to complete the Subhub community demonstrator ready for deployment to EMEC in the next couple of months. Once at EMEC it is intended to use the FORESEA funding to conduct a phased set of sea trials to demonstrate that a tidal array can be installed and recovered in a single offshore operation using small vessel with low date rates.

Phase 1b aims to integrate Schottel Hydro SIT-250 turbines providing Subhub with a capacity of 190kW, capable of powering 50 homes. This collaboration includes SME who will be providing their ‘Flipper’ support structure for bi-directional flow, Platform Operation Module (POM), for controlling the platform at EMEC and Subsea Transformer Module (STM) to transmit the grid friendly power ashore.

Phase 2a will then move operations over to the Falls of Warness site. The aim is to demonstrate the installation and recovery over a wide spectrum of tidal flow and wave heights since the deployment method uses Subhub’s unique submersible stability characteristics that are less sensitive to extreme conditions.

Phase 2b will demonstrate the long term deployment capabilities, operational stability of its gravity based anchoring system and increased performance characteristics of the turbines which have shown insensitivity to cross flows in tank testing at Flowave. An O&M strategy will be developed for its customers assessing fatigue loads, marine growth and corrosion factors.

Phase 3 will be used to assess the environmental impacts of a longer term deployment and demonstrate the ability of the Subhub to be quickly and easily decommissioned from the site.

Once this testing is complete it is intended to offer the Subhub for sale and re-use it at another site. All going well Subhub will be further developed utilising a test berth at EMEC with a larger capcity machine rated at 1.2MW. QED Naval is in early stage discussions with several collaborative partners who would like to be involved in this larger scale development due to be deployed in 2018.

Hive of activity by Cimpina team at the aft end of the Subhub.Project management team discussing the completion of the Subhub, pictured at the front end of Subhub.Subhub side shell and aft leg of the tripod configuration of Subhub to maintain stability on an uneven seabed.

Cimpina based in Northern Ireland in Belfast Docks have been awarded the build contract for the Subhub. They were among 6 different fabricators contending for the business.

Work commenced in November and the outer shell was taking shape before Christmas. Completion is expected in the first quarter of next year.

Keel laying ceremony with representatives from Cimpina * QED Naval toasting the commencement of build using of Scapa Whiskey (Orkney water of life).

The Community Subhub with a capacity of 200kW using Schottel tidal turbines will be launched and transported up to EMEC where long term testing will be conducted, as part of the FORESEA project, to demonstrate the Subhub’s capabilities with installation and retrieval. The performance of the Subhub and turbines will be monitored. Long term operations and maintenance strategy will be developed to validate the OPEX cost model and hence the LCOE for a Subhub related project.

QED Naval are excited to announce that they have been awarded funding for the open sea testing at the EMEC tidal test sites. This provides access to both the scale tidal test site along with the grid connected Falls of Warness site.

QED Naval have engaged in pre-commercial discussions for a contract at EMEC to carry marine operations at their test site that aims to validate claims of the Subhub tidal platform. These include:

Reduction in the cost of deployment of tidal turbines using a single marine operation to install the turbines ready for operation on the seabed within a broad range and tidal states and wave conditions.

Enhanced power output and site capacity factors.

Retrieval of the system for maintenance in a single marine operation using a low cost multicat vessel over a broad range of conditions.

EMEC Falls of Warness tidal test stie.

Significant site feasibility work has already been carried out by QED Naval as part of the FORESEA application which will ultimately see them connect tidal turbines to the grid for verification of the enhanced performance characteristics provided by the Subhub foundation solution.

GIS mapping tool containing all the flow data, berth positions and bathymetry of the Falls of Warness tidal test site.